Terahertz emission from MBE-grown InGaAs/InP and InAs/GaSb films excited by 1550 nm femtosecond laser pulses
We investigate the performance of molecular beam epitaxy (MBE)-grown Indium Arsenide on Gallium Antimonide (InAs/GaSb) and Indium Gallium Arsenide on Indium Phosphide (InGaAs/InP) as terahertz (THz) radiation emitter when photoexcited by 1550 nm-wavelength femtosecond (fs) laser pulses. The emitted THz radiation of both samples has approximately 2 ps pulse width and 2 THz bandwidth. A 35% higher THz radiation peak-to-peak intensity was obtained from InGaAs/InP compared to InAs/GaSb due to the former's greater resistivity and laser penetration depth. Spectral dips corresponding to water vapor absorption can be observed within the usable frequency bandwidth in the power spectra of the samples. This implies that the samples' THz emission using 1550 nm excitation source can be used for spectroscopic fingerprinting. Our results can be used in the development of cost-effective and compact fs laser-based THz-Time Domain Spectroscopy (THz-TDS) systems.